Gas relief valve for firearms



June 19, 1956 E. M. HARVEY 2,750,849

GAS RELIEF VALVE FOR FIREARMS Filed April 26, 1954 2 Sheets-Sheet 1 36 43 2| I6 31 23 jg ATTOBNE Y5 June 19, 1956 E. M. HARVEY GAS RELIEF VALVEFOR FIREARMS 2 Sheets-Sheet 2 Filed April 26, 1954 INVENTOR. Era-r1 E MH'ELTV E BY WJZMMa Mpwr A TTOENE Y5 GAS RELIEF VALVE FOR FIREARMS EarleM. Harvey, Agawam, Mass., assignor to the United States of America asrepresented by the Secretary of the Army Application April 26, 1954,Serial No. 425,771

2 Claims. (Cl. 89-193) (Granted under Title 35, U. S. Code (1952), sec.266) The invention described herein may be manufactured and used by orfor the Government for governmental purposes without the payment of anyroyalty thereon.

This invention relates to gas systems for automatic firearms and moreparticularly to gas regulators therefor.

When gas operated firearms are used to launch grenades, a breakage ofthe recoiling parts of the firearm is oftentimes experienced. This isdue to the restriction of the gases at the muzzle of the firearm by thegrenade which causes excessive gas pressure to be received by the gascylinder and consequently a high velocity of the operating rod and itsassociated members. From high speed photography, it is determined thatthe velocity of the operating rod is approximately twice as great atrecoil position when a grenade is launched as when a round of serviceammunition is fired.

High speed photographs also reveal that the velocity of the recoilingparts vary from round to round in ammunition of the same lot. Thisvariation is obviously undesirable in automatic weapons as it producesundue intermittent strain on the operating parts through the unevennessof operation. Further, it is sometimes necessary to use a lot ofammunition having a pressure higher than that best suited to the firearmwhich, in firearms having conventional gas systems, oftentimes causesbreakage of parts.

It is, therefore, an object of this invention to provide for gasoperated firearms, a gas regulator device for maintaining the operatinggases of the gas system below a predetermined level.

It is another object of this invention to provide for gas operatedfirearms a gas regulator device for maintaining the gases in the gassystem thereof below a safe pressure during the launching of a grenade.

It is a further object of this invention to provide for gasoperated'firearms a gas regulator device for maintaining its gases inthe gas system below a predetermined level and having time delay meansto retard operation thereof by gases temporarily above the predeterminedlevel of pressure.

It is the specific object of this invention to provide a regulatablevalve easily installed in the gas cylinder of a conventional gas systemfor automatically maintaining the gases therein below a predeterminedpressure.

The specific nature of the invention as well as other objects andadvantages thereof will clearly appear from a description of a preferredembodiment as shown in the accompanying drawings in which:

Fig. 1 is a fragmentary partially cross-sectioned side view of the frontend of a firearm with the gas regulator installed thereon and the reliefvalve shown in normal closed position;

Fig. 2 is similar to Fig. l but showing the relief valve opened byexcessive pressure of the gases in the gas' hired rates Ratent Fig. 5 isa perspective exploded view of the relief valve.

Shown in the figures is a firearm having a barrel 12 and a gas cylinder13 with a gas port 14 providing communication therebetween. The threadedclosure member for the front end of gas cylinder 13 has been removed andthreadably mounted in place thereof is a relief valve 15. Relief valve15 includes a hollow cylinder member 16 suitably threaded at the rearend for mounting to the front end of gas cylinder 13 and having aflatted portion 17 arranged to cooperate with a suitable wrench to aidassembling and disassembling. Provided in the inside of cylinder member16 is a reduced diameter portion 18, arranged between a front shoulder19 and a rear shoulder 20, from which there extends to the outside ofcylinder member 16 a plurality of radial ports 21. Disposed forwardly offront shoulder 19 is a chamber 22 which is terminated by a threadedportion 23 and is provided with a longitudinal channel 24.

Slidably disposed in chamber 22 is a valve member 25 having a rodportion 26 which is slidably received by reduced diameter portion 18, atrio of wing portions 27 which serve to maintain rod portion 26 inalignment with the reduced diameter portion during reciprocation and aforwardly extending cylindrical stud 23 arranged to be received by therear end of a coiled compression spring 29. Wing portions 27 alsoprovide the seat for the rear end of spring 29 and limit the rearwardtravel of valve 25 by the engagement thereof with shoulder 19. Slidablymounted in chamber 22 forward of spring 29 and engaged therewith, is acylindical follower member 30. A lug 33 extends from the circumferenceof follower 30 to be slidably received by channel 24, permittingnon-rotating longitudinal movement of follower 30.

A threaded hole 34 extends axially through follower 30 and arranged forcooperation therewith is an adjustment member 35. Adjustment member 35is provided with a head'portion 36 suitably adapted, as noted by 3'7, toreceive the extractor rim of a cartridge for turning and a rearwardlyadjacent cylindrical bearing portion 33. Also a threaded portion 39cooperable with hole 34 and a shank portion 40 extends rearwardly fromsuch threaded portion for engageable cooperation with stud 23 forlimiting the forward movement of valve member 25 to where rod portion 26unblocks ports 21. Rotatably and slidably disposed on bearing portion 38is a cylindrical mounting member 41 having a portion 42 of similardiameter as cylinder 16 and a threaded portion 43 of smaller diameter.Portion 43 extends rearwardly from an annular shoulder 44 formed by thejunction thereof with portion 42 and is arranged to threadably cooperatewith portion 23 of cylinder 16. Portion 42 is provided with lateralholes 45, arranged to receive a spanner wrench, and an annular groove46, rearwardly adjacent shoulder 44 which receives a split friction ring47 for securing mounting member 41 against displacement to cylinder 16.

Extending through bearing portion 38 is a radial pin 48 one end of whichprojects from such bearing portion to be selectively received by aseries of notches 49 in the rear end of mounting member 41. Pin 48 isarranged to permit restricted slidable movement of adjustment member 35,in respect to mounting member 41, to provide for movement of such pin inand out of notches 49. Provided around the perimeter of the front end ofmounting member 41 is a series of inscribed numbers 51 which progressserially from l-4 and are so arranged that an index mark 52 in headportion 36 of adjustment member 35 aligns with one thereof when pin 48is received in one of the notches 49. A stop pin 50 extends from therear end of mounting member 41 for engagement with pin 48 to permit asingle rotation of adjustment member 35.

The first of the numbers 51 is arranged to be indicated by index mark 52when adjustment member 35 is rotated to bring'follower 3b contiguous therear end of mounting member 41 and pin 43 is in position to be receivedby one of notches 59. The other numbers 51 are arranged to increase anadjustment member 35 is turned to move follower .30 against spring 2;and thereby bring greater resilience against valve member25. The bias ofspring 29 against follower 3t), and so rearwardly against adjustmentmember 35, holds'the end of pin '48 resiliently in a selected one of thenotches 49.

Thus, relief valve 15 is adjusted 10 a desired gas pressure by theinsertion of the extractor rim of a cartridge in slot 37 and turningadjustment member 35 thereby to one of the four adjustment positions.The adjustment positions, as hereinbeforc explained, are identified bythe alignment of indcxmarlc 52 With one of the numbers 51, and indexingis achievedtby'the reception of pin into the associated of notches 49.Yfhenever the gas sure received by gas cylinder 13 is over and above thepredetermined pressure, either through excessively powered cartridges orthrough the restriction of the muzzle of the firearms by a grenademounted thereon, tl e. gas pressure overcomes the preadjusted tension ofspring 29 to the extent that valve member 25 is'forced rearwardiy untilrod portion 25 thereof unblocks radial ports 21. Thereby, excessivegases in gas cylinder 13 are expelled into the atmosphere reducing thepressure in the gas cylinder to the predetermined value. The forwardmovement of valve member 25 is limited by the engagement of the end ofstud 28 thereof with the end of shank portion ll of adjustment member35.

it will be noted that valve member 25 must travel some distance beforerod portion 26 thereof vents the gases out of port '21. Thus, surgeWaves with temporary excessive peak pressures do not actuate valvemember 25 suiliciently to vent gases to the atmosphere as the wave willhave receded and the pressure on the valve member reduced accordinglybefore such valve member has had time to unblock ports The inertia ofspring 29 also cooperates with the resiliency thereof in damping thesurge waves.

it is elearl" apparent from the foregoing that there is here providedfor a gas operated firearm, improved means for automatically maintainingthe operating gases of the cylinder at an adjustable level, which isrugged in construction, is easily installed, and is handily regulatable.

Although a particular embodiment of the invention has been described indetail herein, it is evident that many variations may be devised withinthe spirit and scope thereof and the following claims are intended toinclude such variations.

claim:

A gas regulator for a firearm having a gas cylinder, including a bodymember arranged to be threadably mounted to the gas cylinder, said bodymember being provided with a bore communicating with the gas cylinderand a larger diameterchamber extending forwardly therefrom, a pluralityof ports extending radially from said bore to the outside of said bodyand intermediate the ends of said bore, a valve member slidable in saidchamber, a rod portion on said valve member slidably received by saidbore to releasably block said ports, and arranged to be moved to a portsunblocked position by gases in the gas cylinder, means for limiting themovement of said valve to a ports blocked position, the end of said rodbeing positioned beyond said port when said valve is in said portblocked position whereby said valve member is movable an interval beforesaid ports are unblocked by said rod position, a compression coil springmounted in said chamber for cooperation with said valve member toresiliently hold said valve in said ports blocked position, a mountingmember threadably mounted in the front end of said body member, anadjustment member mounted for rotation in said mounting member, afollower threadably mounted on said adjustment member and arranged forslidable nonrotating movement in said chamber against said spring whensaid adjustment member is rotated whereby the gas pressure required tomove said valve member to said ports unblocked position is regulatable,a shank portion on said adjustment member extending rearwardly to beengageable by said valve for limiting forward movement thereof to saidports unblocked position, a pin mounted radially in said adjustmentmember'and being'receivable in one of a plurality of notches in saidmounting member for index'ng said adjustment member, said pin beingresiliently held in a selected one of said notches by the bias of saidspring against said follower, and means for indicating the one of'saidnotches in which said pin is re ceived.

2. For a firearm having a gas cylinder, a gas regulator including a bodymember threadably mounted to the gas cylinder, said body member beingprovided with a longitudinal bore communicating with the gas cylinder, alarger diameter chamber extending therefrom and an annular shoulderformed thereby, a plurality of ports extending radially to the outsideof said body from said bore and between the ends thereof, a reciprocablevalve member having a body portion slidably mounted in said chamber anda rod portion slidably mounted in said bore for releasably blocking saidports during movement of said body portion from engagement with saidshoulder to a relief position, said valve member being movablyresponsive to gas'pressure in the gas cylinder, a spring biased againstsaid body portion. to resist movement of said. valve member by said gaspressure, a rotatably mounted adjustment member extending longitudinallyinto said chamber through said spring for engagement by said valvemember when in said relief position, a follower member threadablymounted on said adjustment member for cooperation with said spring toadjust the preload thereof when said adjustment member is rotated, andindent means assisted by said spring for indexing said adjustment memberin one of a series of predetermined positions.

References Cited in the file of this patent UNITED STATES PATENTS

